The present invention relates to an exhaust gas purifier that filters exhaust gas to collect particulates in the exhaust gas.
The number of automobiles has significantly increased and the amount of exhaust gas emitted from internal combustion engines of automobiles is rapidly increasing proportionately. Particularly, exhaust gas emitted from a diesel engine includes substances that cause pollution. The pollution of exhaust gas seriously affects the world environment. Also, it is recently reported that particulates, such as soot, in exhaust gas sometimes become the cause of allergic reaction and declining sperm counts. That is, it is an urgent issue for the human to take measures to remove particulates in exhaust gas.
Several types of exhaust gas purifiers are proposed under such circumstances. As shown in FIG. 11, typical exhaust gas purifier includes exhaust pipes 80a, 80b extending from a diesel engine 79. An inlet unit 81, a filter unit 82, and an outlet unit 83 are arranged on the exhaust pipes 80a, 80b in this order from the upstream toward the downstream. The inlet unit 81, the filter unit 82, and the outlet unit 83 are secured with each other with clip bands 84. The upstream exhaust pipe 80a and the inlet unit 81, and the downstream exhaust pipe 80b and the outlet unit 83 are coupled with clip bands 84, respectively. Each clip band 84 is formed of a C-shaped ring 84a, and a screw 85 is tightened at its separate portion. Each screw 85 tightens the corresponding clip band 84, which securely couples the inlet unit 81, the filter unit 82, and the outlet unit 83 with one another.
The filter unit 82 accommodates a honey comb filter 86 for collecting particulates exhausted from the diesel engine 79. The filter 86 has through holes defined by cell walls arranged in grid-like pattern. Either end of each through hole is sealed with sealing material to form a checkered pattern. When exhaust gas passes through the filter 86, particulates are trapped by the cell walls.
If an automobile is driven for a long period with the filter 86 mounted on the automobile, particulates, such as soot, accumulate on the filter 86, which increases the load on the diesel engine 79. To solve this problem, particulates accumulated on the filter 86 need to be removed.
To remove the particulates, the filter unit 82 is removed from the inlet unit 81 and an outlet unit 83. Then, the filter 86 is heated by, for example, a heater, to remove the accumulated particulates. The filter unit 82 of vehicles such as buses needs to be frequently (once a day) removed from the vehicle to regenerate the filter 86 since large amount of particulates are accumulated.
However, in the conventional exhaust gas purifier, an operator needs to loosen the screws 85 and remove the clip bands 84 to remove the filter unit 82, which is burdensome. Further, the filter unit 82 of a heavy vehicle, such as commercial busses, is heavy. Thus, attaching and detaching the filter unit 82 in the above mentioned method is very troublesome. Also, when the vehicle is driven for a long period, the filter unit 82 becomes very hot. Thus, the filter unit 82 needs to be sufficiently cooled down before removing it from the vehicle. This further increases time required for removing the filter.
Further, most vehicles such as buses are not equipped with exhaust gas purifiers. Thus, it may be proposed that an exhaust gas purifier be mounted on an existing bus that has no exhaust gas purifier. However, heavy vehicles such as buses that have large engine displacement have large amount of particulates in exhaust gas. Thus, it is required to mount large exhaust gas purifiers on heavy vehicles. Therefore, it is difficult to prepare a space for placing an exhaust gas purifier.
Accordingly, it is an objective of the present invention to provide an exhaust gas purifier that allows a filter to be easily attached or detached. Another objective is to provide an inexpensive exhaust gas purifier for a bus that is easily mounted on a bus without taking additional space for placing the exhaust gas purifier.